1. Field of the Invention
The invention relates to an apparatus for heat welding two overlapping waterproof membranes to each other, and is directed more particularly to such an apparatus provided with improved structure for welding along outside edges of the area to be covered with the membranes.
2. Description of the Prior Art
It is known to provide an apparatus for heat welding two overlapping waterproof membranes attached to a surface, such as a roof top, deck, terrace, or other surface. See, for example, U.S. Pat. No. 6,325,126, issued Dec. 4, 2001, to James Rubenacker et al.
The '126 patent relates to a machine for effecting continuous heat welds for binding an upper membrane to a lower membrane underlying in part the upper membrane. To effect the welds, the machine described in the '126 patent is provided with nozzle means which directs hot air onto the weld area. The upper overlapping membrane is heat sealed to the lower overlapped membrane along the overlap portion to seal the two membranes together. To effect the weld, the nozzle means is moved by the machine between the two membranes, under an edge of the upper membrane.
The aforementioned U.S. Pat. No. 6,325,126 (commonly owned by the assignee herein) is incorporated herein by reference.
While the apparatus shown and described in the '126 patent effects “field seam welding” quite well, that is, welding two membrane strips together, it is not well suited for welding the outboard-most strip outboard-most edge to an outer edge of the supporting roof, or other structure, that is, “edge welding”. Such edge welding is customarily accomplished by a machine devoted wholly to edge welding, or done by hand. There is thus a need for a machine which is adapted for membrane field seam welding and, in addition, for edge welding in a quick and easy fashion.